The permanent alteration of the colour of keratinous fibres, in particular human hair, by the application of hair dyes is well known. In order to provide the consumer with the hair colour and the intensity of colour desired, a very complex chemical process is utilized. Permanent hair dyeing formulations typically comprise oxidative hair dye precursors, which can diffuse into the hair through the cuticle and into the cortex where they can then react with each other and suitable oxidising agents to form the end dye molecules. Due to the larger size of these resultant molecules they are unable to readily diffuse out of the hair during subsequent washing with water and/or detergents; hence delivering a consumer-desired permanency of colour. This reaction typically takes place in an aggressive environment at approximately pH 10 in the presence of an alkalizing agent and in the presence of an oxidizing agent. Moreover, the consumer repeats this process regularly in order to maintain the desired hair colour and shade and the intensity of colour and to ensure continual, even coverage of the hair including coverage of new hair growth.
The manufacturer of such products is also required to work within a large number of constraints. Since these products are being placed in direct contact with the consumers' skin, the potential exists for accidental contact with the eye or for ingestion (for example), which can occur during the dyeing process. Therefore, the formulation must meet rigorous safety requirements and not induce any allergic reactions. In addition to meeting these requirements, the products must also be optically and olfactory pleasing to the consumer. In particular, the products also need to meet certain physical parameters in order to ensure that the product can be easily applied to the hair by the consumer to provide the desired effect, without unintentional staining of the consumers' clothes, skin particularly along the hair line or other objects.
The manufacturer is also required to provide the hair colouring consumer a large range of different resulting colours. Some consumers may just wish to enhance the natural colour of the hair, whilst others may wish to cover grey or completely alter the hair colour to a different natural appearing hair colour or a ‘synthetic’ appearing hair colour. Consequently, the manufacturer may provide over twenty different formulations, of varying colours and shades, to address the range of consumer specific needs. These formulations have to be individually formulated and are typically complex formulae containing a mixture of different dye compounds. As a result the manufacture of such product ranges can be costly and complex.
However, despite the fact that commercial hair dyeing products have been available for many years, the products still exhibit a number of consumer-related deficiencies.
Typically permanent hair dye products will contain an alkali, typically a source of ammonia. This serves the purpose of swelling the hair allowing the entry of the dye precursor molecules into the hair and also improves the lightening effect of the oxidising agent, which is typically hydrogen peroxide. However, ammonia is also volatile and its associated odour is extremely unpleasant to the consumers' of such products, particularly as these hair dye products are used in close proximity to the nasal region. Hence, it would be highly desirable to provide an oxidative hair colouring and/or bleaching composition, which delivers the consumer required lightening level and colour, but which has reduced or eliminated the detectable ammonia odour.
In fact another deficiency area in current hair colouring products is the provision of hair colouring products which deliver the required hair lightening effect. Delivering the required level of lightening is particularly important in order to provide the full range of colour shades demanded by the consumer, especially for blonde shades and grey coverage. Such products pose particular difficulties to the manufacturer, as they usually require the use of high levels of oxidising agent and ammonia in order to deliver the required lightening effect. However, in additional to the problems associated with the presence of high levels of ammonia in these products, as discussed herein above, the presence of these high levels of ammonia and/or oxidizing agent also affect the condition of the hair and may in some cases induce mild skin irritation on the scalp. In particular, the hydrophilicity of the hair surface is increased during the colouring process, which alters the sensory perception of the hair and its overall manageability during, immediately after colouring and during the subsequent wash and styling cycles until the next colourant application. Hence, it would also be highly desirable to provide an oxidative hair colouring and/or bleaching composition which delivers the required lightening and/or colour without unnecessary hair damage.
Moreover, in order to provide a product which the consumer can easily apply to the hair without dripping onto the skin, clothes or bathroom or salon surfaces, hair colourant products must be designed such that the applied composition has a certain required viscosity. This is either achieved by providing the dye composition and the oxidizing composition as so called thin-thin type liquid formulations which are thickened upon mixing, or, where at least one of the components, either the dye composition or the oxidizing composition, preferably the dye composition, is provided as a thickened formulation which thickens the total composition upon mixing. These thickened compositions can be achieved by the use of a gel network system which provide the desired thickness to either the dye composition or the oxidizing composition or, preferably both compositions. Furthermore, such gel networks are highly desirable as they also provide additional benefits of a cream like texture, conditioner like feel and appearance, smooth rinse and improved hair feel. Such thickened gel network systems are described in WO2007/102119, EP1878469 and EP1832273. These compositions have a viscosity range typical for retail applications which is in the region of 1 Pas to 8 Pas.
In the professional hair salon market, the hair colour professionals typically do not use predetermined combinations of dye and oxidizing compositions or kits as in the retail market. Instead, the hair salon professionals are able to use any combination of commercially available dye and oxidizing compositions. For the professional market, the available oxidizing compositions are typically provided with a variety of viscosities. Consequently, the dye compositions that are combined with the oxidizing compositions need to be formulated to ensure that they are able to thicken the oxidizing compositions to the required viscosity independent of the viscosity of the starting composition of the oxidizing agent.
In addition, in the professional salon the mixed dye and oxidative compositions are typically much thicker than the mixed compositions provided for the retail market and are typically in the range of 9 to 16 Pas. This is to enable the hair salon professionals to use a variety of techniques to apply the composition in order to provide their clients with the desired results. Typically this is delivered using the brush and bowl technique. Compositions have a viscosity typical to retail applications are considered not acceptable by hair colour professionals.
However, certain professional thickened compositions comprising such gel network systems have been found to exhibit a phenomenon whereby after application to the hair, the composition tends to crack away from the root along the length of the hair strand away from the root. As a result the roots do not necessarily receive the required amount of composition in order to deliver the desired result. Particularly for regular hair colourant users, virgin hair growth coverage at the roots is essential for a satisfactory outcome and this problem needs to be addressed, without the necessity for the hair salon professional to continuously check and reapply the composition to the roots to ensure complete coverage. This problem of lack of effective root adhesion is further exacerbated with compositions comprising hydrogen peroxide and carbonate oxidizing systems.
Hence it would be desirable to provide the consumer, particularly the hair salon professional with a hair colorant product, which in addition to delivering the required lightening, colour deposition, has the required rheology and viscosity such that it can be utilised by hair salon professionals and which does not exhibit any cracking away from the roots during or after application of the composition on the hair.
It has now been surprisingly found that oxidative hair colouring compositions comprising at least one oxidizing agent, a specified gel network thickener system comprising a specified tertiary system, and a polysaccharide and polyol as defined herein having the required viscosity and ionic strength can be used for professional hair colour applications while exhibiting excellent hair root adhesion.